Hiroko Kano, often referred to as Hiroko Senpai by her junior colleagues, is a central figure in the romantic comedy series that continues in Ayaka is in Love with Hiroko 2nd Stage. She is a senior sales manager at a company, a role in which she is widely respected and known for her professional competence and serious demeanor. In the workplace, she presents as a capable and responsible leader who mentors younger staff members like Ayaka. However, this public-facing persona is carefully maintained to conceal a significant part of her private life. Outside of work, Hiroko is a closeted lesbian who frequents a local lesbian bar, where she has developed a reputation as a womanizer. Her decision to remain secretive about her sexuality stems from a painful past incident at work, which made her cautious about revealing her true self in a professional environment. This duality between her guarded corporate identity and her more liberated social life is a defining source of internal conflict.

Hiroko's personality is a study in contradictions that become the primary engine for the story's comedy and drama. She is often described by viewers and characters as being frustratingly dense when it comes to matters of the heart, frequently misinterpreting the overt romantic advances of her kouhai, Ayaka, as platonic gestures or confusing them as being aimed at other people. This obliviousness is so pronounced that it becomes a major obstacle in their relationship. Beneath this dense exterior, however, lies a deep-seated fear of vulnerability and causing harm. In the second stage of the story, where she and Ayaka have begun living together, this fear manifests as an extreme reluctance to be physically intimate, as she has vowed not to make a move on her beloved Ayaka lightly, fearing she might hurt her. This hesitation, born from a misplaced sense of protective responsibility and a desire to be "perfect," paradoxically leads to Ayaka feeling unwanted and anxious, driving a wedge between them. Her inability to communicate her feelings and her tendency to pull away when confronted with emotional situations highlight a character who is far more secure in her professional identity than in her personal relationships.

Hiroko's motivations are rooted in a desire for stability and a fear of repeating past mistakes. She is deeply concerned with maintaining her respected image at work, which is why she remains closeted. In her relationship with Ayaka, her primary motivation shifts to a protective one; she is terrified of being the cause of pain for someone she loves, so she withholds parts of herself, including her physical desires, leading to a pattern of self-sabotage. Her role in the narrative is that of the emotionally guarded senior who must learn to lower her defenses. Her key relationships include her sister, whose wedding becomes a catalyst for Hiroko to finally come out to her family; the owner of her favorite lesbian bar, who offers her advice; and most importantly, Ayaka, whose persistent love and willingness to initiate difficult conversations eventually force Hiroko to confront her own fears.

Over the course of the second stage, Hiroko undergoes significant development. Initially paralyzed by her commitment to being a flawless, non-threatening partner, her character arc is one of gradual emotional awakening. Through a series of misunderstandings, a trip to Hawaii, and a climactic confrontation orchestrated by Ayaka, Hiroko is pushed to finally speak her mind. She works up the courage to come out to her sister and acknowledges that her fear of being hated has prevented her from being truly open. This breakthrough allows her to move past her self-imposed restrictions. By the conclusion of the series, Hiroko finally reconciles with Ayaka, initiates physical intimacy, and begins to envision a shared future with her, moving beyond the paralysis of her "perfect complex" to embrace a more authentic and communicative partnership. While she possesses notable professional abilities as a manager, her most significant strengths are her capacity for genuine care, which she eventually learns to express more directly, and her willingness, however slow, to change for the sake of love.